Meyers K, Seachord C
Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman 99164-6520.
Thromb Haemost. 1990 Oct 22;64(2):319-25.
Platelets from cattle with the Chediak-Higashi syndrome (CHS) have a platelet dense granule deficiency. One hypothesis for the platelet dense granule deficiency is that the granule is simply not formed in CHS megakaryocytes (MK). Alternative hypotheses include that the granule is assembled in CHS MK but a functional amino-nucleotide-cation storage complex cannot be formed or that the dense granule or its precursor fuses with other granules. This study was undertaken to determine if membrane proteins specific for platelet dense granules can be identified in membranes of other granules in CHS platelets. Platelets were disrupted; a mixed-granule fraction and alpha-granule enriched, mitochondrial-enriched, and dense granule-enriched subfractions were obtained. Membrane proteins in these intact granules were radiolabeled and the granule underwent hypotonic lysis. Membrane proteins were extracted from granule "ghosts", separated, and then visualized by autoradiography. Three major proteins were identified in platelet dense granule membrane subfractions. Two of these proteins could be identified in membrane extracts from the mixed-granule fraction from normal platelets. They could neither be identified in extracts from the mixed granule fraction of CHS platelets nor in membranes from alpha granule-enriched and mitochondrial-enriched subfractions. The absence of dense granule membrane proteins in membranes of other organelles within CHS platelets suggests that fusion of dense granules or its precursor with other granules cannot account for the platelet dense granule deficiency in CHS platelets.
患有Chediak-Higashi综合征（CHS）的牛的血小板存在血小板致密颗粒缺陷。关于血小板致密颗粒缺陷的一种假说认为，致密颗粒在CHS巨核细胞（MK）中根本未形成。其他假说包括致密颗粒在CHS巨核细胞中组装完成，但无法形成功能性的氨基核苷酸阳离子储存复合物，或者致密颗粒或其前体与其他颗粒融合。本研究旨在确定CHS血小板中其他颗粒的膜上是否能识别出血小板致密颗粒特有的膜蛋白。将血小板破碎；获得混合颗粒组分以及富含α颗粒、富含线粒体和富含致密颗粒的亚组分。对这些完整颗粒中的膜蛋白进行放射性标记，然后使颗粒进行低渗裂解。从颗粒“空壳”中提取膜蛋白，进行分离，然后通过放射自显影进行可视化。在血小板致密颗粒膜亚组分中鉴定出三种主要蛋白。其中两种蛋白可在正常血小板混合颗粒组分的膜提取物中鉴定出来。它们既不能在CHS血小板混合颗粒组分的提取物中鉴定出来，也不能在富含α颗粒和富含线粒体的亚组分的膜中鉴定出来。CHS血小板中其他细胞器的膜中不存在致密颗粒膜蛋白，这表明致密颗粒或其前体与其他颗粒的融合不能解释CHS血小板中的血小板致密颗粒缺陷。
